Fire hose nozzles are used by fire fighters for supplying water or other liquids to extinguish fires. A common method of extinguishing fires is to direct a flow of liquid, usually water, onto the fire and often the surrounding area. The flow rate may have to be reduced or increased, depending on the changing character of the fire. Thus, nozzles are needed that provide a variety of flow rates.
In addition, the shape or flow pattern of the flow of liquid produced by the nozzle may impact its effectiveness in fighting a fire. A flow of fluid that includes a consistent velocity throughout the fluid stream produces a solid column of liquid, which is preferable to a column of water that includes varying degrees of velocity throughout the flow of liquid. Water streams having a consistent velocity travel further and are more accurate than water streams having an inconsistent velocity. Prior art fire hose nozzles suffer from the inability to produce a variable stream of liquid that which has a consistent velocity throughout the flow of fluid. For nozzles which are able to adjust the rate at which fluid flows through the nozzle, the inner diameter of the nozzle is typically deformed in a manner that produced grooves, bumps or other irregularities. These irregularities lead to inconsistent velocities within the flow of fluid. In addition, prior art nozzles do not overcome the “wall effect,” which results in a slower velocity for those portions of the fluid that are proximate to an interior wall of the nozzle. Accordingly, it would be desirable to have a nozzle which provides a smooth column of water at variable flow rates.